Related papers: Issues in determining alpha_s from hadronic tau de…
While the idea of using the operator product expansion (OPE) to extract the strong coupling from hadronic $\tau$ decay data is not new, there is an ongoing controversy over how to include quark-hadron "duality violations" (i.e., resonance…
There are some indications from recent determinations of the strong coupling constant alpha_s and the gluon condensate that the Operator Product Expansion may not be accurate enough to describe non-perturbative effects in hadronic tau…
We discuss the quantitative impact of duality violations on the determination of the strong coupling constant from hadronic tau decays, based on a preliminary analysis of OPAL data.
We discuss sum-rule determinations of $\alpha_s$ from non-strange hadronic $\tau$-decay data. We investigate, in particular, the reliability of the assumptions underlying the "truncated OPE strategy," which specifies a certain treatment of…
Being a determination at low energies, the analysis of hadronic tau decay data provides a rather precise determination of the strong coupling alpha_s after evolving the result to M_Z. At such a level of precision, even small…
Hadronic tau decays offer the possibility of determining the strong coupling alpha_s at relatively low energy. Precisely for this reason, however, good control over the perturbative QCD corrections, the non-perturbative condensate…
Evidence is presented for the necessity of including duality violations in a consistent description of spectral function moments employed in the precision determination of $\alpha_s$ from $\tau$ decay. A physically motivated ansatz for…
Several different analysis methods have been developed to determine the strong coupling via finite-energy sum-rule analyses of hadronic $\tau$ decay data. While most methods agree on the existence of the well-known ambiguity in the choice…
Non-perturbative effects have a small but non-trivial impact on the determination of the strong coupling from hadronic $\tau$ decay data. Several approaches have been proposed to take these into account, the two most important of which are…
We discuss why, in the determination of $\alpha_s(m_{\tau}^2)$ from hadronic $\tau$ decays, two important assumptions made in most of previous analyses, namely the neglect of higher-dimension condensates and of Duality Violations (DVs),…
We discuss the issue of duality violations in hadronic tau decay. After introducing a physically motivated ansatz for duality violations, we estimate their possible size by fitting this ansatz to the tau experimental data provided by the…
Recently, we extracted the strong coupling, $\alpha_s(m_\tau^2)$, from the revised ALEPH data for non-strange hadronic tau decays. Our analysis is based on a method previously used for the determination of the strong coupling from OPAL…
Using the spectral functions measured in $\tau$ decays, we investigate the actual numerical impact of duality violations on the extraction of the strong coupling. These effects are tiny in the standard $\alpha_s(m_\tau^2)$ determinations…
Employing our previous framework to treat non-perturbative effects self-consistently, including duality violations, we update the determination of the strong coupling, \alpha_s, using a modified version of the 1998 OPAL data, updated to…
We present a new framework for the extraction of the strong coupling from hadronic \tau decays through finite-energy sum rules. Our focus is on the small, but still significant non-perturbative effects that, in principle, affect both the…
An updated measurement of alpha_s(m_tau) from ALEPH tau hadronic spectral functions is presented. We report a study of the perturbative prediction(s) showing that the fixed-order perturbation theory manifests convergence or principle…
We present an update of the measurement of alpha_s(m_tau) from ALEPH tau hadronic spectral functions. We report a study of the perturbative prediction(s) showing that the fixed-order perturbation theory manifests convergence problems not…
I review the notion of the quark-hadron duality from the modern perspective. Both, the theoretical foundation and practical applications are discussed. The proper theoretical framework in which the problem can be formulated and treated is…
OPE constraints are studied as a means of distinguishing between the versions of the I=1 vector spectral function extracted from (i) inclusive I=1 hadronic electroproduction cross-sections and (ii) inclusive I=1 hadronic tau decay data,…
We discuss a preliminary study of the impact of duality violations on extractions from tau decay data of the D=6 VEVs which determine chiral limit Standard Model K-->pi pi matrix elements of the electroweak penguin operators.